121 



Determination of carbon dioorid in soils. 

 (Percentage of dry soil.] 



The result* submitted by Ellett and Brown agree very satisfactorily. Those sub- 

 mit ted by Van A \<\ ine are markedly lower, especially in the case of soil No. 2. Appar- 

 ently tin- amount of carbon dioxid which remained in solution in the latter work is 

 the cause of the |,,\v. T n-ults. Evidently Knorr's apparatus is efficient for the deter- 

 mination of comparatively slight amounts of carbonates; however, it is desirable that 

 further w.rk !> done aloni; this line, and the associate referee would therefore recom- 

 mend, that it be continued with certain modifications for at least another year. 



REPORT ON POTASH. 



I'.y I', H. K,,ss, Referee. * 



The w..rk mi pi.ta.-h for the past year lias included cooperative tests of the regular 

 otlii-ial method in comparison with the phonphomolybdic volumetric method, and, 

 in addition, the reft-ree, associate referee, and some cooperating chemists have made 

 comparative tests with some special methods which will be described in the latter 

 portion of thi< report. 



Twenty laboratories expressed a desire to take part in the cooperative work on 

 P >ia-h sample-, but reports were received from only eight laboratories. 



Two .-ample.-, were sent out for analysis to each laboratory taking part in the work, 

 sample No. 1 being high-grade commercial sulphate of potash, while sample No. 2 

 was a mixed fertili/er, the ingredients of which were acid phosphate, cottonseed meal, 

 dried Mood, potassium chlorid, and a small amount of magnesium sulphate. 



The following instructions with regard to the work were sent out to all cooperating 

 chemi>is. the details .if the volumetric method being those given by the referee for 

 !?; and 1907, Mr. A. L. Knisely, who had given much time and attention toastudy 

 of the phosphomolybdic method. 



OUTLINE OF ASSOCIATION POTASH WORK. 



Sample No. 1. Commercial sulphate of potash. 



Sample No. 2. A complete mixed fertilizer, the nitrogen of which is derived from 

 cotton.-eed meal and dried blood. 



Pota.-h in these samples should be determined both by the official method and the 

 pn>{>osed volumetric method involving use of phosphomolybdic acid. 



